[Q] Switching between 2 phones on the same service?

Trying to get a Google/Nexus phone running AOSP Android.
Is there a way I can switch back and forth between my DroidX and this other phone on my Verizon (CDMA) service? I will not be using both phones at the same time.
With unlocked GSM phones, it is just a matter of moving the SIM card over...